MathCalc.java

package org.codedifferently;

import java.util.Random;

public class MathCalc {

    //helper class to generate a random number given a lowerBound and upperBound
    public int generateRandomNumber(int lowerBound, int upperBound) {
        Random random = new Random();
        return random.nextInt((upperBound - lowerBound) + 1) + lowerBound;
    }

    //generates taxRate  by picking a random number and converting the % to decimal.
    public double generateTaxRate() {
        return (generateRandomNumber(1,20)) * 0.01;
    }

    //calculates the final total by adding taxes and subtracting discounts.
    public double calculateFinalTotal(double subTotal, double taxRate, double discountRate) {
        return Math.round(subTotal + (subTotal * taxRate) - (subTotal * discountRate));
    }

    //Calculates remaining budget by subtracting the two arguments and rounding.
    public double calculateRemainingBudget(double budget, double finalTotal) {
        return Math.round(budget - finalTotal);
    }

    //Calculates the absolute value.
    public double calculateAbsoluteValue(double num) {
        return Math.abs(num);
    }

    //Generates couponDiscount by generating a random number, then converting the % to decimal.
    public double generateCouponDiscount() {
        return generateRandomNumber(1,50) * 0.01;
    }
}